Marvin Harrison Jr. of the Cardinals collapses on the field after a header hit in a loss to the Packers

Arizona Cardinals rookie wide receiver Marvin Harrison Jr. collapsed on the field, leaving Sunday's 34-13 loss to the Green Bay Packers early after accidentally hitting his head on a pass play.

The game took place in the second quarter at Lambeau Field. Cardinals quarterback Kyler Murray targeted Harrison with a pass over the middle. Packers cornerback Jaire Alexander broke up the pass and threw Harrison to the turf. As Harrison fell, the crown of his helmet hit linebacker Isaiah McDuffie in the thigh, causing his head to snap back.

Harrison stood up after the hit, visibly dazed. He immediately fell back onto the grass.

He went to the medical tent on the sidelines and then went to the locker room with athletic trainers. The Cardinals announced before halftime that he was being diagnosed with a concussion and ruled him out before the start of the third quarter.

The injury is a blow to Harrison in his sixth NFL game and to a Cardinals team that has struggled to move the ball. A first-round draft pick, Harrison was Arizona's top receiver in Week 5 with 17 catches for 279 yards and four touchdowns. The Cardinals went into halftime trailing the Packers 24-10. They scored just one field goal over the rest of the game and committed two turnovers on consecutive drives en route to a 21-point loss. That put them at 2-4 this season.